I am not familiar with Emmy but I'm guessing that the usual work flow will involve an interactive shell with many calls to `render` to display expressions in infix notation so that you can better check if the expression you typed is actually what you meant to type.
The infix notation, although arbitrary and not as logically simple as other notations, is almost universal in the math-speaking world. Most mathematicians and engineers have have years of experience staring at infix expressions on blackboards, and disseminate new knowledge using this notation, and do new calculations in this notation.
In reading your reply, I think that maybe some tooling that could auto-insert corresponding infix-like comments above an AST-like syntax could be a solution for writing such code in Zig.